<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>克隆优化节点操作</title>
</head>
<body>
    <p id="box1">old</p>

    <script>
        for(var i = 0; i<3; i++){
            var p = document.createElement('p')
            p.innerHTML = 1
            document.body.appendChild(p)
        }

        // 优化
        var oldP = document.getElementById('box1')
        for(var j= 0; j<3; j++){
            var newP = oldP.cloneNode(false)
            newP.innerHTML = j
            document.body.appendChild(newP)
        }
    </script>
</body>
</html>